Leber congenital amaurosis comprises a group of early onset childhood retinal dystrophies, characterized by vision loss, nystagmus, and severe retinal dysfunction. To date, 15 causative genes have been identified that account for the heterogeneous presentation and clinical course. Knowledge of key aspects of phenotype and clinical course can contribute to the determination of a precise genetic etiology using genetic testing. Gene-based therapies are emerging, and knowledge of a patient's genotype is essential. A review of clinical presentation and disease course, their correlation to specific genotypes, and underlying physiological mechanisms, coupled with the latest results of human gene therapy trials, will assist the clinician in patient diagnosis and counseling.